It is known to disperse, by reactive compounding, a thermosetting polymer in a thermoplastic matrix, whether this is in an internal mixer or in a twin-screw extruder, in order to obtain a thermoplastic/thermosetting blend that has improved mechanical properties in comparison to those of the thermoplastic matrix alone.
Mention may be made, for example, of the thesis report of Mrs Laure Meynié (defended on Jun. 9, 2003 before the Institut National des Sciences Appliquées in Lyons) entitled “Evolution et contrôle de la morphologie d'un melange thermoplastique/thermodurcissable polymerisé sous cisaillement” [Evolution and control of the morphology of a thermoplastic/thermosetting mixture polymerized under shear] (see in particular page 19 of this report), which presents the use of reactive extrusion for obtaining such dispersions. One drawback of the dispersion processes mentioned in this report is that a compatibilizing agent, such as a copolymer containing acrylate or methacrylate blocks, is required in order to compatibilize immiscible polymers, it being specified that the major part of this report relates to a mixture of miscible polymers and does not give details on the shear and profile characteristics of the extrusion screw elements, nor on the injection points of the reinforcing agents used. Another drawback of the dispersions obtained in this report lies in their relatively inhomogeneous nature in the thermoplastic matrix and also in the relatively coarse morphologies obtained for the epoxy resin nodules dispersed in an immiscible thermoplastic matrix (in general, with nodules having a number-average size greater than 10 μm and with demixing between the two phases).
Mention may also be made of the patent document U.S. Pat. No. 5,709,948 which presents thermoplastic compositions for example based on a polyolefin reinforced by an epoxy resin, which is dispersed via reactive compounding in a twin-screw extruder or in an internal mixer with a crosslinking agent of the resin. This document gives no indication on the morphology obtained for the epoxy resin nodules, whether in terms of fineness or homogeneity of the dispersion.
Document WO-A1-2007/001609 relates to a thermoplastic vulcanisate comprising an elastomeric discontinuous phase which is predominantly composed of a vulcanized EPDM rubber and which is dispersed in a thermoplastic continuous phase.
Document EP-A1-0 529 799 teaches the use of an elastomeric discontinuous phase which is predominantly composed of an SBS thermoplastic elastomer (containing polystyrene-polybutadiene-polystyrene blocks) and which is partially dispersed in a thermoplastic continuous phase using a compatibilizing agent.
Document US-A1-2005/0277737 teaches the use of an elastomeric discontinuous phase which is predominantly composed of a crosslinked nitrile rubber (NBR) and which is dispersed in a thermoplastic continuous phase.